There are a several types of surgical procedures in which a soft tissue graft is secured within a tunnel formed in a bone. A number of surgeons reconstruct a damaged cruciate ligament using a patellar tendon graft. The disclosures of U.S. Pat. Nos. 5,139,520 (Rosenberg), 5,139,499, (Small, et al.), and 5,163,940 (Bourque) are incorporated herein by reference.
After harvesting, the patellar tendon graft comprises a length of soft tissue secured at either end to a bone plug. The bone plugs typically have a rectangular or trapezoidal cross-section and then are carved into a round shape to fit into circular holes drilled into the tibia and femur. Alternatively, larger round holes are drilled to accommodate the non-round shape of the bone plugs.
Other surgeons utilize round dilators of increasingly larger diameters to form a round tunnel in a femur by compaction. The bone plugs are shaped into a matching round cross-section, and are sized using a bar having holes formed therein of different indicated diameters, one of which is selected by the surgeon as corresponding to the hole formed in the bone.
Bone plugs typically are secured within a bone tunnel using an interference screw. Difficulty may be encountered during the insertion of an interference screw between the bone plug and the wall of the bone tunnel. The screw sometimes converges or diverges from its intended path which may weaken its anchoring ability and may even fracture the bone plug. A screw guide sold under the trademark TRAILBLAZER, available from Acufex Microsurgical, Inc., Mansfield, Mass., is a circular punch having a conical distal tip which is inserted between the bone plug and the tunnel wall prior to inserting an interference screw to encourage proper placement of the screw.
Another conventional device utilizes a round punch with a semi-circular offset that is inserted into the bone tunnel prior to inserting the bone plug. The round offset forms a curved groove which may assist subsequent screw placement. Another goal of this device is to minimize rotation of the bone plug during screw insertion.
The above-described techniques still require the extra step of shaping the harvested bone plug into a circular cross-section. Further, multiple instruments must be inserted and removed to provide a separate channel for an interference screw.
If unshaped, the bone plugs do not conform to the cross-section of the tunnel. The spaces between the plug and the tunnel may retard bone fusion and healing.